The present invention relates to a prestressed tubular connection for concentric members and a tool for making such connection within the well.
Prior to the present invention it has been known to mechanically or hydraulically deform a first tubular member into gripping and sealing engagement with a second tubular member which surrounds the portion of the first tubular member to be deformed. This is disclosed in the B. S. Minor et al. U.S. Pat. No. 2,134,311 wherein the top of a casing string is rolled into tight gripping and sealing engagement with a surrounding casing head. U.S. Pat. No. 4,580,426 discloses a sleeving apparatus in which a sleeve is rolled into engagement within a heat exchanger tube. U.S. Pat. No. 2,460,580 discloses the use of pressure to form a tubular member on opposite sides of a partition and U.S. Pat. No. 5,010,952 discloses hydraulically preforming a tubular member into a wellhead housing so that a compression preload is introduced into the joint. U.S. Pat. Nos. 4,902,048 and 4,902,049 discloses a connection between tubular members in which the deformation is made by tightening a binding band on a slotted outer member to deform the outer member into a groove in the inner member.
In oil and gas wells it has long been known to set combination anchors and packers around the exterior of a string to seal between the exterior of the string and the interior of the surface surrounding the string. These patents generally suggest a resilient sleeve which is compressed axially to cause it to seal against the interior surface surrounding the string and upper and lower slips which are set by wedges moving under the slips responsive to mechanical forces or pressure derived forces to cause the slips to move outward into gripping engagement with the interior surface. U.S. Pat. Nos. 2,189,703; 2,274,093; 2,467,801; 2,467,822; and 2,681,112 disclose examples of such anchor packer structures of the prior art.
A summary of the recent work in offshore drilling and making connections during such operations is disclosed in the Society of Petroleum Engineers Paper Nos. SPE 23054, 23057 and 23058 presented at Offshore Europe held in Aberdeen, Scotland, Sep. 3-6, 1991.